The present invention relates to a developing apparatus using a monocomponent developer and, particularly, to such apparatus using a non-magnetic monocomponent developer.
The conventional developing method of dry tape which is utilized for electrophotography or electrostatic recording, etc., is classified generally into two approaches, one using a bicomponent (dual component) developer containing toner and carrier and the other using monocomponent type developer containing no carrier. The former method can provide a relatively stable, good copy image. However, there are disadvantages of degradation of carrier, variation of mixing ratio of toner to carrier, maintenance difficulties of the copying machine and difficulties in minimizing the size of machine.
In view of this, the monocomponent type developer is desirable. The conventional monocomponent type developer is usually a toner containing some material corresponding to carrier and, when the toner is moved magnetically, the material is a magnetic material. However, since such magnetic material is usually opaque, its pigment is a disadvantage in a color development, and makes it difficult to obtain a sharp color image. Therefore, the developer for color development should not contain magnetic material. In such case, however, one problem how to move the developer smoothly along a predetermned direction. In addition, the known monocomponent type developer is generally not suitable to develop an image based on a low contrast original image or characters written by using hard pencils, etc. That is, the known monocomponent developer is not suitable to develop an area image or a line image whose concentration is selectively changed.